The pump should be able to run dry without damage. However, if you are disconnected from city water and the fresh water tank has sufficient water in it and the pump is pumping water from the faucets and the faucets are shut off and there are no leaks anywhere the pump is likely bad.
One possibility to check for a loose connection between the pump intake and the tank. If it is sucking air this could happen. If you have a winterizing tube at the pump check to be sure that valve is completely closed.
Chuck - Sparta, TN
2012 Jay Flight 22FB, 2 x Honda EU2000i
2013 GMC Yukon XL Denali AWD
EDUCATION is what you get when you read the fine print.....
EXPERIENCE is what you get when you don't.